The production of hydrogen and oxygen by the electrolysis of water has been practised on the industrial scale since the beginning of this century. In recent years, the economics of hydrogen and oxygen production have been influenced by the cost of electrical power. As a result, cheaper larger scale production of hydrogen has been carried out using coal, oil and natural gas. However, due to increasing prices and limited availabilities of these fossil fuels, other methods of hydrogen production have been considered. These methods include the use of solar energy, off-peak electrical power and possibly nuclear power.
By using waste materials as an energy source to generate electricity at a negligible operation cost, the electrolytic hydrogen and oxygen can be readily produced on a very competitive basis (although still on the smaller scale) when compared with current practices. Furthermore, the electrolyte method has certain intrinsic advantages. The method is well proven with high energy conversion efficiencies of 45-65 percent. Higher efficiencies could be obtained by the implemetation of the latest technology. High purity gases are readily produced. The equipment can be operated automatically in a safe manner and continuous gas production can be ensured by the use of back-up mains power.
The other aspect of concern is the ultimate disposal of undesirable and some intractable liquid and solid wastes. Since there is no ultimate means of disposal such as complete incineration yet available in Australia, the accumulation of these `difficult` wastes in considerable and causing a very serious environmental problem.
At the present, the dumping of industrial and/or toxic liquid wastes is not permissible at the council tips. Liquid wastes generally include biological, chemical and combustible liquid such as sewage sludge, acids, alkalines, used oils, organic solvents and some highly toxic chemicals and pesticides. Only some non-toxic wastes such as diluted acids which can be treated and neutralised may be transported to a Metropolitan Waste Authority's depot and then disposed of at considerable cost. The remaining waste of a more toxic nature, are presently either stored or dumped illegally. Obviously these methods are unsatisfactory.
The accumulation of many thousands of used rubber tires and enormous amounts of spent cathode linings generated from aluminum smelters also gives rise for concern. Satisfactory disposal facilities for these wastes do not currently exist in the region.
Another type of waste is coal washery reject. Most of this consists of coarse and fine rejects. The former is usually dumped in heaps or used as fill in gullies. The latter which is made up mainly of a slurry of fine coal and soil particles is usually disposed of in settling ponds. Over the decades millions of tonnes of colliery waste have accumulated, taking up large areas of valuable land and sterilizing coal reverses. Furthermore, these dumps can creat problems of dust, fire and water pollution. These wastes could be disposed of by incineration in large, high-temperature furnaces. This method involves a very high initial cost, especially if air pollutants are to be controlled. To operate efficiently, this tye of furnace would require wastes or external fuel containing high levels of combustible materials of high energy content due to its low thermal inertia and need to control combustion stability. On the other hand, smaller and cheaper fluidised-bed incinerators can be operated at lower temperatures without the above disadvantages and are therefore a more acceptable alternative.